Web services are client and server applications that communicate over a network protocol, such as hypertext transfer protocol (HTTP). A web service is a software component provided through a network-accessible endpoint and can be called from other applications. For example, a financial company may have a web service that provides customers to transfer money between bank accounts. The information provided by the web service can be read from a web page and displayed, or read from a stand-alone application on a customer's desktop computer or mobile device.
Representational state transfer (REST) is a style of software architecture for distributed systems, such as the World-Wide-Web. REST-style architectures include clients and servers. Clients can initiate requests to the servers, which can process the requests and return appropriate responses. In REST, requests and responses are built around the transfer of representations of resources. A representation of a resource is typically a hypertext document that captures the current or intended state of the resource. For example, the resource may be mortgage rates from a financial institution.